How to evaluate Ethernet network services when linking locations

Interconnecting three or more sites across a metro or wide area network has traditionally been accomplished via a hub and spoke network using private lines, frame relay or Internet Protocol virtual private networks (IP VPN) over the Internet. However, Ethernet services are a cost-effective alternative that can also support hub and spoke topologies as well as a unique, “any-to-any” network topology.

Both Ethernet methods can achieve secure, high performance multi-site connectivity with full IP transparency, but by weighing the differences in the two methods, you can impact IT operations, management and cost, says Mike Maloney, vice president at Comcast Business Class.

Smart Business spoke with Maloney about considerations and best practices when connecting three or more sites via Ethernet.

Why use Ethernet services in the first place?

Because most applications today are IP-based, you could presume IP VPNs are more suitable than Ethernet VPNs. While both deliver connectivity, there are three benefits of Ethernet VPNs:

• Security — Ethernet services are immune to certain Internet-based threats, such as the popular IP denial of service attacks.

• Quality of service (QoS) performance — Ethernet services run over the service provider’s managed network, resulting in better control, more predictable performance and more service availability.

• IP transparency — Ethernet services don’t require IP routing information to be shared with the service provider, enabling companies to keep their existing IP address with freedom to expand.

What are the advantages of using either hub and spoke or multi-point connectivity?

With hub and spoke, sites connect through the hub site to communicate with any other site. The benefit is centralized traffic routing, requiring simpler and lower cost routers to attach to the spoke sites since these locations only make a direct, point-to-point connection to the hub.

Any-to-any connectivity enables all sites to communicate with each other over the wide area network. One advantage is simplicity in adding new sites to the shared service across the network. Routers at each site automatically discover new sites with no additional device configuration changes.

How can you decide which is better?

In addition to service pricing and availability, assessing your current and future needs will help determine the more appropriate Ethernet service:

• Adding bandwidth — With hub and spoke, you can add more bandwidth until it exceeds the physical speed port, and then, there’s the capital expense of the higher-speed port and possibly additional service cost to upgrade the on-site equipment. However, you can selectively apply bandwidth upgrades to specific spoke sites. With any-to-any, bandwidth is increased at the particular site, which could result in a service disruption at the local site.

• Adding sites — When adding to hub and spoke, the service provider connects the new spoke to the existing hub site, requiring a software configuration change and possibly a reboot. Adding a site to any-to-any doesn’t require service disruption.

• Traffic flow patterns — A hub and spoke approach works well if most of the communications are to a particular site, such as regional sites connecting to a headquarters site or data center. It’s also well suited for centralized IT management of Internet access, email and storage. An any-to-any approach is most sound when regular communications are required between two or more sites.

• QoS performance — With hub and spoke technology, bandwidth, packet latency and packet loss are more granularly engineered and managed per site. Each site’s bandwidth and QoS performance can be unique with each site’s costs more accurately allocated.

An any-to-any implementation enables bandwidth to increase or sites to be added without impacting other connected sites. However, since it is a shared resource, bandwidth, management and QoS performance may need to be monitored more closely. This approach also can support many applications requiring different QoS performance such as IP telephony (VoIP) and IP video.

Mike Maloney is vice president at Comcast Business Class. Reach him at [email protected]

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